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Parameterized the Zcb extension
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- Added `usingCompressedSuiteB` to enable/disable `Zcb` extension.
- This parameter depends upon existing `usingCompressed` parameter.
- By default `Zcb` is disable in RocketCore.
- Passed this parameter along with `usingBitManip` and `usingMulDiv` to RVCDecoder enable/disable the decoding of corresponding `Zcb` instructions.

Signed-off-by: Abdul Wadood <[email protected]>
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@Abdulwadoodd
Abdulwadoodd committed May 21, 2023
1 parent 323d57d commit bb50f29
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Showing 3 changed files with 47 additions and 22 deletions.
66 changes: 44 additions & 22 deletions src/main/scala/rocket/RVC.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,7 @@ class ExpandedInstruction extends Bundle {
val rs3 = UInt(5.W)
}

class RVCDecoder(x: UInt, xLen: Int, useAddiForMv: Boolean = false) {
class RVCDecoder(x: UInt, xLen: Int, useAddiForMv: Boolean = false, usingBitManip: Boolean = false, usingMulDiv: Boolean = false, usingCompressedSuiteB: Boolean = false) {
def inst(bits: UInt, rd: UInt = x(11,7), rs1: UInt = x(19,15), rs2: UInt = x(24,20), rs3: UInt = x(31,27)) = {
val res = Wire(new ExpandedInstruction)
res.bits := bits
Expand Down Expand Up @@ -63,14 +63,17 @@ class RVCDecoder(x: UInt, xLen: Int, useAddiForMv: Boolean = false) {
else ld
}
def zcb_q0 = {
def lbu = Cat(lbImm, rs1p, 4.U(3.W), rs2p, 0x03.U(7.W))
def lh = {
val func3 = Mux(x(6), 1.U(3.W), 5.U(3.W))
Cat(lhImm, rs1p, func3, rs2p, 0x03.U(7.W))
if (usingCompressedSuiteB){
def lbu = Cat(lbImm, rs1p, 4.U(3.W), rs2p, 0x03.U(7.W))
def lh = {
val func3 = Mux(x(6), 1.U(3.W), 5.U(3.W))
Cat(lhImm, rs1p, func3, rs2p, 0x03.U(7.W))
}
def sb = Cat(rs2p, rs1p, 0.U(3.W), 0.U(3.W), lbImm(1,0), 0x23.U(7.W))
def sh = Cat(rs2p, rs1p, 1.U(3.W), 0.U(3.W), lhImm(1,0), 0x23.U(7.W))
inst(Seq(lbu, lh, sb, sh)(x(11,10)), rs2p, rs1p, rs2p)
}
def sb = Cat(rs2p, rs1p, 0.U(3.W), 0.U(3.W), lbImm(1,0), 0x23.U(7.W))
def sh = Cat(rs2p, rs1p, 1.U(3.W), 0.U(3.W), lhImm(1,0), 0x23.U(7.W))
inst(Seq(lbu, lh, sb, sh)(x(11,10)), rs2p, rs1p, rs2p)
else inst(Cat(lwImm >> 5, rs2p, rs1p, 2.U(3.W), lwImm(4,0), 0x3F.U(7.W)), rs2p, rs1p, rs2p) // unimp
}
def sd = inst(Cat(ldImm >> 5, rs2p, rs1p, 3.U(3.W), ldImm(4,0), 0x23.U(7.W)), rs2p, rs1p, rs2p)
def sw = inst(Cat(lwImm >> 5, rs2p, rs1p, 2.U(3.W), lwImm(4,0), 0x23.U(7.W)), rs2p, rs1p, rs2p)
Expand Down Expand Up @@ -112,22 +115,41 @@ class RVCDecoder(x: UInt, xLen: Int, useAddiForMv: Boolean = false) {
def rtype = {
val funct = Seq(0.U, 4.U, 6.U, 7.U, 0.U, 0.U, 0.U, 3.U)(Cat(x(12), x(6,5)))
val sub = Mux(x(6,5) === 0.U, (1 << 30).U, 0.U)
val mul = Mux(Cat(x(12), x(6,5)) === 6.U, (1 << 25).U, 0.U)
val opc = Mux(x(12), Mux(x(6), 0x33.U(7.W), 0x3B.U(7.W)), 0x33.U(7.W))
def mul = {
if(usingMulDiv && usingCompressedSuiteB) Mux(Cat(x(12), x(6,5)) === 6.U, (1 << 25).U, 0.U)
else 0.U
}
def zca = inst(Cat(rs2p, rs1p, funct, rs1p, opc) | sub | mul, rs1p, rs1p, rs2p)
def zcb_q1 = {
def zextb = inst(Cat(0xff.U, rs1p, 7.U(3.W), rs1p, 0x13.U(7.W)), rs1p, rs1p, rs2p)
def sextb = inst(Cat(0x604.U, rs1p, 1.U(3.W), rs1p, 0x13.U(7.W)), rs1p, rs1p, rs2p)
def sexth = inst(Cat(0x605.U, rs1p, 1.U(3.W), rs1p, 0x13.U(7.W)), rs1p, rs1p, rs2p)
def not = inst(Cat(0xFFF.U, rs1p, 4.U(3.W), rs1p, 0x13.U(7.W)), rs1p, rs1p, rs2p)
def zextw = inst(Cat(4.U, x0, rs1p, 0.U(3.W), rs1p, 0x3B.U(7.W)), rs1p, rs1p, x0)
def zexth64 = inst(Cat(0x80.U, rs1p, 4.U(3.W), rs1p, 0x3B.U(7.W)), rs1p, rs1p, rs2p)
def zexth = {
if (xLen == 32) inst(Cat(0x80.U, rs1p, 4.U(3.W), rs1p, 0x33.U(7.W)), rs1p, rs1p, rs2p)
else zexth64
def unimp = inst(Cat(lwImm >> 5, rs2p, rs1p, 2.U(3.W), lwImm(4,0), 0x3F.U(7.W)), rs2p, rs1p, rs2p)
if(usingCompressedSuiteB){
def zextb = inst(Cat(0xff.U, rs1p, 7.U(3.W), rs1p, 0x13.U(7.W)), rs1p, rs1p, rs2p)
def not = inst(Cat(0xFFF.U, rs1p, 4.U(3.W), rs1p, 0x13.U(7.W)), rs1p, rs1p, rs2p)
def zexth64 = inst(Cat(0x80.U, rs1p, 4.U(3.W), rs1p, 0x3B.U(7.W)), rs1p, rs1p, rs2p)
def sextb = {
if(usingBitManip) inst(Cat(0x604.U, rs1p, 1.U(3.W), rs1p, 0x13.U(7.W)), rs1p, rs1p, rs2p)
else unimp
}
def sexth = {
if(usingBitManip) inst(Cat(0x605.U, rs1p, 1.U(3.W), rs1p, 0x13.U(7.W)), rs1p, rs1p, rs2p)
else unimp
}
def zextw = {
if(usingBitManip) inst(Cat(4.U, x0, rs1p, 0.U(3.W), rs1p, 0x3B.U(7.W)), rs1p, rs1p, x0)
else unimp
}
def zexth = {
if(usingBitManip) {
if (xLen == 32) inst(Cat(0x80.U, rs1p, 4.U(3.W), rs1p, 0x33.U(7.W)), rs1p, rs1p, rs2p)
else zexth64
}
else unimp
}
Seq(zextb, sextb, zexth, sexth, zextw, not)(x(4,2))
}
Seq(zextb, sextb, zexth, sexth, zextw, not)(x(4,2))
else unimp
}
def zca = inst(Cat(rs2p, rs1p, funct, rs1p, opc) | sub | mul, rs1p, rs1p, rs2p)
Mux(Cat(x(12), x(6,5)) === 7.U, zcb_q1, zca)
}
Seq(srli, srai, andi, rtype)(x(11,10))
Expand Down Expand Up @@ -190,9 +212,9 @@ class RVCExpander(useAddiForMv: Boolean = false)(implicit val p: Parameters) ext

if (usingCompressed) {
io.rvc := io.in(1,0) =/= 3.U
io.out := new RVCDecoder(io.in, p(XLen), useAddiForMv).decode
io.out := new RVCDecoder(io.in, p(XLen), useAddiForMv, usingBitManip, usingMulDiv, usingCompressedSuiteB).decode
} else {
io.rvc := false.B
io.out := new RVCDecoder(io.in, p(XLen), useAddiForMv).passthrough
io.out := new RVCDecoder(io.in, p(XLen), useAddiForMv, usingBitManip, usingMulDiv, usingCompressedSuiteB).passthrough
}
}
1 change: 1 addition & 0 deletions src/main/scala/rocket/RocketCore.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,7 @@ case class RocketCoreParams(
useAtomics: Boolean = true,
useAtomicsOnlyForIO: Boolean = false,
useCompressed: Boolean = true,
useCompressedSuiteB: Boolean = false,
useRVE: Boolean = false,
useSCIE: Boolean = false,
useBitManip: Boolean = false,
Expand Down
2 changes: 2 additions & 0 deletions src/main/scala/tile/Core.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,7 @@ trait CoreParams {
val useAtomics: Boolean
val useAtomicsOnlyForIO: Boolean
val useCompressed: Boolean
val useCompressedSuiteB: Boolean
val useBitManip: Boolean
val useBitManipCrypto: Boolean
val useVector: Boolean = false
Expand Down Expand Up @@ -86,6 +87,7 @@ trait HasCoreParameters extends HasTileParameters {
val usingAtomicsOnlyForIO = coreParams.useAtomicsOnlyForIO
val usingAtomicsInCache = usingAtomics && !usingAtomicsOnlyForIO
val usingCompressed = coreParams.useCompressed
val usingCompressedSuiteB = coreParams.useCompressedSuiteB && usingCompressed
val usingBitManip = coreParams.useBitManip
val usingBitManipCrypto = coreParams.hasBitManipCrypto
val usingVector = coreParams.useVector
Expand Down

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